Structural Engineering Terms

Architect

The designation reserved by law for a person or organization professionally qualified and duly licensed to perform architectural services.  Architects design the spaces, appearances, and functions of buildings.  Architects employ structural engineers to design the structure of these buildings to withstand gravity and lateral forces.

Building Official

A representative of governmental authority employed to inspect construction for compliance with applicable codes, regulations, ordinances and permit requirements.

Client

The person or organization employing an architect or engineer and to whom these professionals are responsible.

Codes

Regulations, ordinances, or statutory requirements of a government relating to building construction and occupancy, generally adopted and administered for the protection of public health, safety and welfare.

Compression

Axial force causing shortening of a structural member. Force acts parallel to the longitudinal axis of the member and pushes inwards on the member. 

Computer-Aided Design

Commonly abbreviated as CAD, or CADD for computer-aided design and drafting. A term applied to systems or techniques for design and drafting that utilize integrated computer hardware.

Contractor

The designation reserved by law for a person or organization qualified and duly licensed to provide contracting services. The contractor is the individual or entity with whom the owner enters into a construction contract to provide the construction services for a specific project.

Cripple Wall

A short height of wall, typically occurring in residential home construction, between the ground floor and the foundation. In older construction, cripple walls are typically not covered with sheathing and therefore are unable to transmit shear forces from the walls above to the foundation below. This creates a weak link in the lateral load path that may result in a partial collapse of the wall framing over the unsheathed height.

Dead Loads

Static loads that are permanently present, such as the weight of a structure. Act downwards (gravity load). 

Deflection

Movement or curvature of a loaded structural member.

Feasibility Study

A detailed investigation and analysis conducted to determine the financial, economic, technical, or other advisability of a proposed project.

Foundation Bolts

Steel bolts, typically required in residential construction, that connect the wood framing above to the concrete foundation below. In older construction, these bolts are generally missing or are spaced too far apart. This creates a weak link in the lateral load path that may result in a horizontal offset between the structure and the foundation after an earthquake.

Girder

A large beam made of metal or concrete, and sometimes of wood, that supports the ends of smaller beams.

Gravity Loads

Vertical loads from the weight of static or transient portions or occupants of a structure. Acts downward on a structure. 

Lateral Loads

Loads from wind or earthquakes that put horizontal forces on a structure.

Live Loads

Transient loads to structural members, such as occupants, furniture, or cars.

Member

A structural unit such as a wall, column, beam, or tie, or a combination of any of these.

Moment

Force that causes bending, or curvature, of a structural member.

Non-Structural Elements

Elements of a building that are not structural elements, but are attached to them, such as ceilings, mechanical and electrical equipment, and cladding.

Owner

A person or entity who retains professionals for design and construction services. This person or entity typically owns or is the lessee of the building site or project premises.

Primary Structural System

The system of elements in a structure that provides the main path of resistance to all the loads applied to it. The structural engineer designs the primary structural system.

Prime Consultant

The party hired by the Owner, and the leader of the design team charged with the design of a new or remodeled facility. The prime consultant can be either an architect or an engineer. 

Professional Engineer

The designation of a registered engineer who provides engineering services. These services may include, but are not necessarily limited to, development of project requirements; creation and development of project design; preparation of drawings, specifications and bidding requirements; and providing professional services during the construction phase of the project.

Richter Scale

A measurement of earthquake magnitude defined by Professor Charles Richter. The magnitude scale measures the energy released during an earthquake, and was intended to be rating of a given earthquake independent of the place of observation. Since it is calculated for measurements on seismograms, it is properly expressed in ordinary number and decimals. Magnitude was originally defined as the logarithm of the maximum amplitude on a seismogram written by an instrument of specified standard type at a distance of 100 kilometers (62 miles) from the epicenter. Because the scale is logarithmic, every upward step of one magnitude unit means multiplying the recorded amplitude by 10, and corresponds to approximately 30 times more energy released. The largest known earthquake magnitude is 9.2, recorded in both Chile and Alaska. By contrast, intensity scales, such as the Modified Mercalli Intensity scale, relate actual damage to intensity. These measurements may take many days due to the field work involved.

Shear

The force causing deformation of a solid body in which a plane in the body is displaced parallel to other planes in the body. Walls are typically designed to resist shear forces, and plywood walls are sometimes termed "shear" by the construction industry.

Shop Drawing

All drawings, diagrams, illustrations, schedules and other data or information that are specifically prepared or assembled by or for a contractor, and submitted by a contractor to an architect or engineer to illustrate in detail some portion of the work.

Slab

A thin structural member, usually of concrete or stone. Also refers to floors or roofs of concrete.

Soft Story

Typically on the first floor level, a story that is weaker and/or more flexible than the stories above it for lateral force resistance. These first stories may taller than the stories above, or may have large wall openings (such as garage doors) while the stories above have solid walls. Earthquakes can cause significant damage to structures with a soft story, as the soft stories often lean or collapse due to their lower stiffness and/or strength.

Structural Element

A single structural member such as a beam, column, wall, brace, truss, or foundation that, when combined with others, forms the structural system.

Structural Engineering

The application of specialized civil engineering knowledge, training, and experience to evaluate, analyze, design, specify, detail, and observe the construction of force-resisting elements of structures. Such expertise includes consideration of strength, stability, deflection, stiffness, ductility, potential modes of failure, and other characteristics that affect the behavior of a structure.

Structural System

An assemblage of framing and bracing members designed to support gravity loads and resist lateral forces.

System Ductility

The relationship of the maximum inelastic drift to the elastic drift. The ability of a structural system to bend without breaking.

Tension

Axial force applied along the length causing elongation of a structural element.

Value Engineering

The process of suggesting alternative systems, materials, and methods to reduce the cost and/or enhance the value of the project.

Water Heater

A domestic appliance used to heat water. In residential construction, these are typically not well braced for lateral movement and can therefore be damaged during an earthquake. Damage to the water heater may result in fire and care should be taken near them following an earthquake. Water heaters should be braced to reduce the risk of fire or explosion. Self-bracing kits are available at hardware stores.